Embodiments of the present invention generally relate to dust boots assemblies and apparatus for providing grease relief for a dust boot. More specifically, the present invention relates to dust boot assemblies and apparatus for providing grease relief for dust boots coupled to greasable joints such as ball-and-socket joints.
Many joint assemblies and compatible dust boots exist for coupling to one or more components (e.g., automobile chassis components). An example of one such prior art joint assembly and compatible dust boot for use with an outer tie rod end of an automobile chassis is depicted in FIG. 2. Specifically, joint assembly 110′ is a ball-and-socket joint assembly, and it is depicted coupled to body 106′ of an outer tie rod end.
Often, dust boots such as dust boot 108′ are coupled to a joint assembly to prevent dirt, dust, water, mud, moisture, and other contaminants from infiltrating the joint and/or the grease present in the joint since such infiltration typically decreases the service life of the joint. Such dust boots typically include a main body such as dust boot body 150′. In the depicted embodiment, dust boot body 150′ has an ovate shape, however, dust boots having alternate shapes including, but not limited to, conical, dome-shaped, hemi-spherical, spherical, and accordion-shaped are also known.
Many such bodies include first and second apertures such as first and second apertures 126′ and 152′, respectively, to facilitate coupling of dust boot 108′ to a joint, a joint assembly, and/or a component coupled thereto (collectively referred to hereinafter as non-dust boot components) while allowing an extension of the non-dust boot component to pass therethrough. Alternate dust boot bodies include an aperture designed to mate with a flanged portion of the housing to which it will be coupled (e.g., the joint housing, joint assembly housing, or the housing of a component coupled thereto).
Coupling of a dust boot to a non-dust boot component may be performed using a variety of methods. One such method is to perform such coupling via one or more O-rings, clamping rings, and/or combinations thereof, which encircle or are otherwise affixed to the exterior portion of the dust boot in contact with the non-dust boot component such that the dust boot is held to the non-dust boot component. For example, such O-rings, clamping rings (e.g., duplex clamping ring 124′), and/or combinations thereof may surround the exterior portion of a dust boot aperture such as first and second apertures 126′ and 152′. Alternatively, such coupling may be performed via inclusion of metal rings, plastic rings, or the like internal to the portion of the dust boot encircling or otherwise affixed to the non-dust boot component (e.g., internal metal ring 156′ or a plastic ring similar thereto).
In the exemplary prior art embodiment depicted in FIG. 2, dust boot 108′ is coupled to body 106′ and joint assembly 110′ by passing ball extension 154′ of assembly 110′ through first aperture 126′ of dust boot 108′ until second aperture 152′ of dust boot 108′ rests atop body 106′. It should be noted that in the embodiment depicted in FIG. 2, the inwardly facing surface of first aperture 126′ and the inwardly facing surface of second aperture 152′ (i.e., the inwardly facing surface of lip 128′ as discussed in greater detail below) have been specifically configured to mate with the outwardly facing surfaces of the portions of the non-dust boot components to which they will be coupled, namely, ball extension 154′ and the upper end of body 106′, respectively. This type of mating configuration is commercially known and it allows dust boot 108′ to be tightly coupled to ball extension 154′ and the upper end of body 106′ via internal metal ring 156′ (or a plastic ring similar thereto) and duplex clamping ring 124′, respectively, as depicted in FIG. 2. This tight coupling prevents or minimizes the potential of infiltration of contaminants into the joint at the locations of such couplings.
In dust boot 108′ depicted in FIG. 2, the inwardly facing surface of second aperture 152′ includes lip 128′ to, inter alia, reinforce the strength and integrity of the seal between dust boot 108′ and body 106′. Lip 128′ includes axial and radial components 158′ and 160′, respectively, located perpendicular to each other. Axial component 158′ has sufficient height to allow a coupler (e.g., a simplex clamping ring, a duplex clamping ring, a desired quantity of O-rings or the like) to encircle same, wherein the coupler is located below the portion of dust boot body 150′ coupled to the distal end of axial component 158′ and located above radial component 160′. In the depicted embodiment, the height of axial component 158′ accommodates the placement of duplex clamping ring 124′ on the external surface thereof. Radial component 160′ provides a stop that prevents duplex clamping ring 124′ from sliding, or otherwise disengaging, from the external surface of axial components 158′. Since dust boot body 150′ includes lip 128′ located at the inwardly facing surface of second aperture 152′, the outwardly facing surface of body 106′ is coupled to the inwardly facing surface of lip 128′ via the method described above. However, dust boots without lips 128′ are commercially available and such dust boots are compatible with the present invention as discussed in greater detail below. In such scenarios, the outwardly facing surface of the non-dust boot component is simply coupled to the inwardly facing surface of the non-lipped edge of second aperture 152′.
Some such joint assemblies, including joint assembly 110′, are greasable (i.e., it is possible to add grease to the joint). Greasing the joint lubricates the joint, thereby facilitating smooth movement of same as such joints are typically made of metal and/or plastic components and, therefore, such joints involve metal to metal contact, plastic to plastic contact, and/or metal to plastic contact. For example, if the joint is a ball-and-socket joint, greasing facilitates smooth movement of the ball relative to the socket and it reduces the friction exerted upon the surfaces of the ball and socket by each other. Greasing of the joint also extends the service life of the joint and helps to expel any dirt, moisture, or other contaminants that may have entered the joint. Greasing also beneficially expels grease which has been previously injected into the joint as such grease tends to thin and otherwise spoil over time.
Dust boots having one or more apertures through a wall of the dust boot such as grease relief aperture 168′ also exist. Such apertures are intended to provide an aperture through which excess grease may exit the internal cavity of the dust boot when over-greasing occurs. In the joint assembly 110′ depicted in FIG. 2, grease may be added to the joint via injection of the grease through grease injection port 112′ using commercially known methods. Grease input through grease injection port 112′ enters assembly cavity 114′ and, upon inputting of a sufficient quantity of grease, the grease is forced between the surfaces of ball 116′ and first and second socket sections 118′ and 119′, respectively, thereby lubricating the external surfaces thereof. Upon injection of a large quantity of grease, the grease will pass around approximately the entire perimeter of ball 116′ as depicted by arrows 120′, the latter of which indicate a typical grease flow. When an excess quantity of grease is injected through grease injection port 112′ (i.e., the joint is over greased), the excess grease exits the area located between the surfaces of ball 116′ and first and second socket sections 118′ and 119′, respectively, and enters boot cavity 122′. Over greasing is often performed intentionally to remove existing, older grease from the joint. If a quantity of grease is injected through grease injection port 112′ that exceeds the combined capacity of assembly cavity 114′, the area between the surfaces of ball 116′ and first and second socket sections 118′ and 119′, respectively, and boot cavity 122′, grease relief aperture 168′ allows the excess grease to be relieved from boot cavity 122′ as depicted by arrows 120′. However, in addition to allowing grease to exit the internal cavity of the dust boot (e.g., boot cavity 122′), apertures such as grease relief aperture 168′ also typically allow contaminants to enter the internal cavity of the dust boot from the environment surrounding the dust boot (e.g., with automobile chassis components, this environment includes mud, water, dirt, dust, and the like present on the roadways), whereupon these contaminants often enter the area between the surfaces of the ball and socket, thereby decreasing the service life of the joint.
Other types of pressure relief boot seals are known for use with joint assemblies such as ball-and-socket type joint assembles. One such boot seal includes a rigid collar member molded into a resilient body member, wherein the rigid collar member has radial and thrust bearing surfaces. The rigid collar member includes axial and radial grooves surrounding the entire periphery of the rigid collar that allow grease present internal to the boot seal to flow to a chamber located between the rigid collar member, a sealing lip, and a component to which the joint assembly is coupled. Upon an accumulation of excess grease internal to this chamber, the sealing lip deflects to allow the grease in the chamber to pass between the sealing lip and the component to which the joint assembly is coupled.